Aerial mounting



March 26, 1946. D. w MITCHELL 2,397,151

7 AERIAL MOUNTING Filed Oct. 15, 1942 INVENTORQ BY D M I WW Patented Mar. 26, 1946 UNITED STATES PATENT OFFICE 2,397,151 AERIAL MOUNTING Douglas W. Mitchell, Ottawa, Ontario, Canada, assignor to Electronic Laboratories; Inc.

Application October 15, 1942; Serial No.- 462,169

My invention relates in'gene'ral to mountings for aeri'als and more particularly to a tiltable mountlngior' aerials which allows the aerial to bend over as thev'ehicleaupon which his mounted passes under trees or. other obstructions.

Myinvention finds particular utility in connectlon witlrmounti'ngaerial's upon the top of-v'ehi'cles which-may be used to travel through woods and undenbrushwhich may" engage the aerial and tilt it back as the vehicle-moves forwardly. The-invention may be used upon'trucks. tanks or any other vehicle which may be used for war purposes.

An object of my invention is the provision of mounting the spring which permits the tiltable mounting to be tilted inside of ahousin which wilLkee'p-the twigs: and bushes from becoming entangled-in-the spaces'between the coils of the spring.

Another-object of my invention is the provision of a tiltablemounting havinga low electrical capacityso' that there is very-little loss of energy passing-from the output of the radio signalling system-over tothe metal vehicle surfac which carries the antenna.

Another object-ofmy invention is the provision of a-tiltable mounting for aerials which maybe operated a'lar e number of times witho t breakin or withoutv requiring replacement.

Another objectormy invention is the provision of a hollow metal tube for conducting the radio frequencyi-romthe radio frequency supply source to theaerial, in which the metal tube also functions as a-housing for the sprin which permits the tlltable Operation of the mounting, so that twigs and branches oftrees cannot become lodged between the spacesof the spring.

Another object of my invention isthe' provision ofa tiltable mounting for aerials which is simple in construction and durable in operation. v

Otherobjects and afuller. understanding of my invention may be had by referring to the following description and claims, taken. in conjunction with the accompanying drawing, in which:

Figurel represents'a side elevational view of a vehicle illustrating my tiltable mounting. positioried onthe top thereof for carrying an aerial;

Figure 2 is a cross-sectional view of my tiltable mounting for an aerial, taken along the line 2-2 of Figure 3;

Figure 3 is a plan View of my tiltabl'e' mounting for aerials;

Figured is a side elevational View of my tiltable mounting for aerials; and I Figure 5 1 5,231 view similar to Figure 2 but shows the tiltable mounting being tilted to substantially a horizontal position.

My tiltable mounting, is illustratedgenerally by theirefe'rence character ill and comprises abase I 3 and a-tiltable sleeve i t which carries the aerial i I. The base l3 may leeounted on a-vehiole top i2 as illustrated in Figure 1. In iasteningmy tiltabl'e mounting to a vehicle surface, a relativelylarge opening 36 is-cut in the vehicle surface andthe marg edges of the base l3 are secured to the marginal edge of the opening 36 by meansof suitable screws29, as illustrated. The base i 3 may comprise any suitabledielectric material and pref erably the-dielectric base should be as large-as possible in order to'make the-capacity small which prevents the escape of radio frequency energy to themeta'ltop l2 of the vehicle. The base I3 may be -made' into a pluralityof. sections comprising the sections l9-, 2ll-and 2|. In this manner, the leakage-resistancemay be kept large. r 4

Ontop of the base section leis mounted a metal resting'plate =1 l and-a contact platelB upon which thetiltablev tube [4 isarranged to be tiltably mounted. Theametal resting plate I! and the contact plate l8 maybesecurely fastened to the topbasesection N by meansof a hollow. sleeve 22 whichextends through all of the base sections 19, 20 and 2 L The outside surface of the'hollow sleeve 22is provided with threads and the metal resting plate I l is arrangedto be threadably connected-to one end ofthe hollow. sleeve 22 and a-nut 23 is arranged-tube threadably connected to the other end of the hollow sleeve for holdingthebasesections I9, 20 and 2| together as well asflthe metal resting plate I! and the contact plateon top of thebase section- [9.

The tilt'able tube M has an enlarged bell portion IS on, thebottom end thereof which engages thermet'al resting plate H. The bell portion 15 may be welded such. as indicated by th reference characterit to the lower endof the tiltable tube M. The peripheral edge of the metal resting plate I I is chamfered or rounded and the lower peripheral edge of the enlarged bell portion I5 is arrangedto rest upon this ,chamfered or rounded per p eral edge of, the metal resting plate in order toima'ke a good metal tometal contact. In actual ractice, the diameter of the metal restingplate l! is slightly larger than the diameter of the peripheral lower edge of the enlarged bell portion l5 so that there is a slight tendency for the .enlarged bell portion l5 to rockupon the chamfered or rounded peripheral edge of the contact metal resting plate [1. By means of: this construction, a good metal to metal contact between the metal resting plate I! and theperipheral lower edge of theenlarige'd bell portion l 5 is always guaranteed.

Mounted within, the tiltable tube it is aspring 32 having its lower end resting upon a stop member 33 that fits within the opening provided in the top central part of the enlarged bell portion I5. The upper end of the spring 32 presses against an anchoring member 3! which is securely fastened to the upper end of a cable BI) which extends downwardly through the spring 32 and w h has its lower end 25 securely anchored to an anchoring screw 24. As illustrated in Figures 2 and 5 of the drawing, the anchoring screw 24 may be hollow for a portion of its length and in actual practice I provide for brazing or otherwise fastening the lowerend of the cable 30 in the hollow portion of the anchoring screw 24. Similarly, the upper end of the cable 30 may be brazed or other suitably fastened in the anchoring member 3|. The wire 28 which leads from the radio signallin system may be fastened to the anchoring screw 24 by means of two nuts 26 and 21'. The tension of the spring 32 may be varied by turning the nut 26 with reference to the anchoring screw 24, after which the wire 28 and the nut 21 may be tightened for holding the wire securely to the anchoring screw 24. The upper end of the tiltable tub I4 may be provided with a chuck 34 for releasably holding the aerial I I upon the turning of the chuck sleeve 35.

In operation, when the vehicle passes under a limb of a tree or other bush, the antenna II may be tilted back until the vehicle passes under the obstruction. When the obstruction is cleared the antenna II is immediately raised to its vertical position. During the time that the tiltable tube I4 is being tilted. a good metal to metal contact is permanently made so that the radio communication is not interrupted. The enlarged bell portion I5 since it has a larger diameter than the diameter of the tiltable tube I4. provides for giving an initial stability to the aerial II before it is tilted back upon striking a branch of a tree or other obstruction. The base section 2| which is the section that is connected to the metal top of the vehicle, may be made large in diameter to reduce the capacity of the mounting to thereby prevent any loss of radio frequency energy escaping over to the metal top I2 oi the vehicle. The tiltable tube I4 protects the spring 32 from direct contact with twigs or other obstructions that might lodge between the spaces of the coils of the spring and thereb keeps the mounting in complete operative condition under all adverse conditions. In addition, the tiltable tube I4 acts as a conductor for the high radio frequency energy and hence high frequency energy tends to flow to the outer surface of a conductor by reason of electrical skin effect. In other words, in my invention there are no parts which are external of the tiltable tube I4 through which the high radio frequency would tend to pass by reason of the electrical skin effect. Therefore, the tiltable tube I4 not only performs a mechanical function to protect the spring from becoming clogged up with twigs and other objects, but also provides a good electrical conduction path for the high radio frequency to the aerial I I.

Although I have shown and described my invention with a certain degree of particularity, it is understood that changes may be made therein without departing from the spirit of the invention which are included within the scope of claims hereinafter set forth.

I claim as my invention:

1. In an aerial having a plurality of hollow members, the improvement of connecting joint means for the hollow members, said improvement comprising first engaging means on one of the hollow members, second engaging means on another hollow member, said engaging means being adapted to engage each other and support the hollow members in a substantially fixed extended position with respect to each other, resilient means in one of the hollow members, bendable means connected to the resilient means in the said one of the hollow members and extending through the first and second engaging means to the said another hollow member, said bendable means and said resilient means exerting a constraining force upon said hollow members and constraining the first and second engagin means together to hold the hollow members in the said substantially fixed extended position, said bendable means upon movement of the hollow members from the said substantially fixed extended position being subjected to a bending movement and said resilient means being subjected to an axial movement free from said bending movement, terminal means having a contact portion engaging the said another hollow member, said bendable means being connected to the terminal means and constraining the said contact portion against said another hollow member, at least one of said engaging means having an outwardly sloping surface against which the other engaging means contact to limit longitudinal movement between the hollow members.

2. In an aerial having a plurality of hollow members, the improvement of connecting joint means for the hollow members, said improvement comprising first engaging means on one of the hollow members, second engaging means on another hollow member, said engaging means being adapted to engage each other and support the hollow members in a substantially fixed extended position with respect to each other, resilient means in one of the hollow members, bendable means connected to the resilient means in the said one of the hollow members and extending through the first and second engaging means to the said another hollow member, said bendable means and said resilient means exerting a constraining force upon said hollow members and constraining the first and second engaging means together to hold the hollow members in the said substantially fixed extended position, said bendable means upon movement of the hollow members from the said substantially fixed extended portion being subjected to a bending movement and said resilient means being subjected to an axial movement free from said bending movement, said resilient means having its end which is next to the engaging means blocked in the said one of the hollow members and having its remote end connected to the bendable means, thereby being subject to compression, terminal means having a contact portion engaging the said another hollow member, said bendable means being connected to the terminal means and constraining the said contact portion against said another hollow member, at least one of said engaging means having an outwardly sloping surface against which the other engaging means contact to limit longitudinal movement between the hollow members.

3. A tiltable mounting for securing an aerial to a vehicle surface having an opening therein comprising, in combination, a base comprising dielectric material for covering the said opening, means for securing the marginal edge of said base to the marginal edge of the said opening, a metal resting plate mounted on the outside surface of the base, a hollow sleeve extending through the base for holding the resting plate on the base, a flexible cable having a first end portion and a second end portion, said first end portion extending through the hollow sleeve, terminal means fastened to the first end portion of the cable which extends through the hollow sleeve, said terminal means engaging the hollow sleeve and anchoring the said first end portion of the cable to the hollow sleeve, a tiltable hollow metal tube having a first end with a socket arranged t tiltably rest on the metal resting plate and having a second end arranged to support the aerial, a spring positioned in the hollow tube, said spring having one end engaging the tiltable hollow tube and having the other end engaging the second end portion of the flexible cable for resiliently urging the first end of the tiltable hol low tube against the resting plate and thereby permitting the hollow metal tube to be tilted with reference to the resting plate under the action of the spring, said flexible cable means upon a tilting movement of the hollow tube being subjected to a bending movement and said spring means being subjected to an axial movement free from said bending movement, said metal resting plate having a diverging peripheral edge against which the socket engages, said socket resting on the diverging peripheral edge and limiting longitudinal movement between the hollow tube and the said plate.

DOUGLAS W. MITCHELL. 

